Ultrabright narrow-band telecom two-photon source for long-distance quantum communication

Niizeki, Kazuya; Ikeda, Kazuhiro; Zheng, Ming-Yang; Xie, Xiaozhu; Okamura, Kotaro; Takei, Nobuyuki; Namekata, Naoto; Inoue, Shuichiro; Kosaka, Hideo; Horikiri, Tomoyuki

doi:10.7567/apex.11.042801

Cited by 30 publications

(21 citation statements)

References 35 publications

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“…The coherence timescale should be at least more than several nanoseconds, which are longer than detection time resolution. For such a timescale up to tens of nanoseconds, the SPDC nonlinear crystal is located inside an optical cavity, and the paired bandwidth has been decreased by 10 MHz [6][7][8][9][10][11][12][13].…”

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confidence: 99%

“…1, we set a natural linewidth (full-width at half-maximum, FWHM) Γ 0 and a dephasing rate γ 13 between energy levels 1 and 3. For driving fields, we set the power of a coupling (P c 180 mW) and a pump laser (P p 3 mW), and consequently the Rabi frequencies (Ω c 4.78γ 13 and Ω p 1.45γ 13 ) and the effective Rabi frequency (Ω e ) and effective dephasing rate (γ e ). A far off-detuned pump beam Δ p 48.67γ 13 is a similar condition in a cold atomic case.…”

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confidence: 99%

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Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters

Jeong

Kim

2019

J. Opt. Soc. Am. B

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confidence: 99%

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confidence: 99%

Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters

Jeong

Kim

2019

J. Opt. Soc. Am. B

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“…The atomic-ensemble-based schemes hold an advantage over spontaneous parametric down-conversion processes (SPDC) in nonlinear crystals and optical parametric oscillators [20,65,66], that also rely on engineered PM, as the photons generated in atomic ensembles are inherently narrowband and atom-resonant, making them suitable for quantum metrology [67] and repeater-based communication [2,68,69]. With purely atomic photonpair source, potentially difficult engineering of cavitybased SPDC can be avoided [70,71].…”

Section: Comparison With Spdcmentioning

confidence: 99%

Superradiant parametric conversion of spin waves

et al. 2019

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Atomic-ensemble spin waves carrying single-photon Fock states exhibit nonclassical many-body correlations in-between atoms. The same correlations are inherently associated with single-photon superradiance, forming the basis of a plethora of quantum light-matter interfaces. We devise a scheme allowing the preparation of spatially-structured superradiant states in the atomic two-photon cascade using spin-wave light storage. We thus show that long-lived atomic ground-state spin waves can be converted to photon pairs opening the way towards non-linear optics of spin waves via multi-wave mixing processes.Spatially extended atomic ensembles are a particularly versatile medium allowing generation and control of light with widely varying properties. Fulfilment of the phasematching (PM) condition facilitates efficient generation, storage and retrieval of single photons. Superradiance is inherently linked to the phase-matched emission and, in particular, spin waves (SW) that store information about light in the atomic coherence are superradiant Dicke states N −1/2 j e iKrj |g 1 . . . h j . . . g N [1]. In practice, the Λ scheme of atomic levels, which forms the basis of the Duan-Lukin-Cirac-Zoller quantum entanglement distribution protocol [2], is well-known for its capabilities to generate photon pairs with both non-trivial temporal [3] and spatially-multimode structure [4]. There, light is interfaced with a coherence between two metastable ground-state sublevels.An alternative ladder or diamond schemes allow generation of two-color photon pairs, and attract much attention [5-8] also for single-photon storage [9, 10] and in Rydberg-blockaded media [11,12]. In those cases the associated SWs lie between a ground state and an excited atomic state and are intermediate steps in the generation of a photon pair. More complex manipulations of those SWs, such as temporal [13][14][15][16][17] and spatial [18] mutli-SW beamsplitters demonstrated for ground-state SWs, remain elusive. Such control would allow SW-based enginieering of photon pair emission, possibly also extensible to deterministic quantum nonlinear optics based on Rydberg atoms [19].Here we show that the properties of a phase-matched cascaded atomic decay can be engineered via proper preparation of the atomic SW state. In particular, we treat the SW prepared in the Raman process as one of the fields participating in the parametric conversion, similarly as a pump field in a spontaneous parametric downconversion (SPDC) in nonlinear crystals [20]. Hitherto schemes necessarily required that the atom starts and ends the wave-mixing processes in the same ground state, as dictated by the principles of energy and momentum conservation. This requirement can be leveraged if the ensemble is first prepared in a superposition state, or in other words some coherence is present.We generate a strong atomic coherence (SW) between |g and |h via Raman interaction in the Λ scheme, as depicted in Fig. 1(a). The two pump fields (P1 and P2), as in Fig. 1(b), then transfer the coherence |g h|...

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“…Two major physical mechanisms are used to produce biphotons: the spontaneous parametric down conversion (SPDC) [18][19][20][21][22][23][24][25][26][27][28][29][30] and spontaneous four-wave mixing (SFWM) [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] . The SPDC is employed for nonlinear crystals.…”

Section: Introductionmentioning

confidence: 99%

Room-temperature biphoton source with a spectral brightness near the ultimate limit

Chen,

Hsu,

Huang

et al. 2021

Preprint

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The biphotons, or pairs of time-energy entangled photons, generated from a hot atomic vapor via the process of spontaneous four-wave mixing (SFWM) have the following merits: stable and tunable frequencies as well as linewidth. Such merits are very useful in the applications of long-distance quantum communication. However, the hot-atom SFWM biphoton sources previously had far lower values of generation rate per linewidth, i.e., spectral brightness, as compared with the sources of biphotons generated by the spontaneous parametric down conversion (SPDC) process. Here, we report a hot-atom SFWM source of 960-kHz biphotons with a generation rate of 3.7× 10 5 pairs/s. The high generation rate, together with the narrow linewidth, results in a spectral brightness of 3.8× 10 5 pairs/s/MHz, which is 17 times of the previous best SFWM result and also better than all known SPDC results. The all-copropagating scheme employed in our biphoton source is the key improvement, enabling the achieved spectral brightness to be about one quarter of the ultimate limit. Furthermore, this biphoton source had a signal-to-background ratio (SBR) of 2.7, which violated the Cauchy-Schwartz inequality for classical light by about two-fold. Although an increasing spectral brightness usually leads to a decreasing SBR, our systematic study indicates that both of the present spectral brightness and SBR can be further enhanced. This work demonstrates a significant advancement and provides useful knowledge in the quantum technology using photons.

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Ultrabright narrow-band telecom two-photon source for long-distance quantum communication

Cited by 30 publications

References 35 publications

Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters

Proposed narrowband biphoton generation from an ensemble of solid-state quantum emitters

Superradiant parametric conversion of spin waves

Room-temperature biphoton source with a spectral brightness near the ultimate limit

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